Sources of indoor air pollutants

Indoor air pollutants can originate from various sources, both inside and outside the building. These pollutants can be either anthropogenic (caused by human activities) or natural.

Combustion sources

Combustion processes, such as those from gas stoves, fireplaces, and smoking, release various pollutants into the air:

• Carbon monoxide (CO)
• Nitrogen dioxide (NO2)
• Particulate matter (PM_2.5 and PM₁₀)
• Volatile organic compounds (VOCs)

Building Materials and Furnishings

Many building materials and furnishings can emit VOCs, including:

Paints and varnishes

These often contain solvents that release VOCs as they dry.

Adhesives and sealants

Used in construction and renovations, these can emit VOCs for extended periods.

Carpets and flooring

Some carpets and flooring materials can release VOCs, especially when new.

Furniture

Certain types of furniture, particularly those made with pressed wood products, can emit formaldehyde, a type of VOC.

Household Products

A wide range of household products can contribute to indoor air pollution.

Biological Sources

Biological pollutants are living organisms or substances derived from them that can cause health problems.

• Mold: Mold spores can trigger allergies and respiratory problems. Mold growth is often associated with dampness and poor ventilation.
• Bacteria and viruses: These can cause infections and illnesses.
• Dust mites: Microscopic creatures that feed on dead skin cells and can trigger allergies and asthma.
• Pet dander: Tiny flakes of skin shed by pets that can cause allergies.

Indoor activities

Cooking

Cooking activities can release PM, VOCs, and other pollutants into the air.

Personal Activities

Smoking, using hobby materials, and even breathing can contribute to indoor air pollution.

Outdoor environment

Soil

• Radon: A naturally occurring radioactive gas that can seep into buildings from the ground and is a leading cause of lung cancer.